Heat pump apparatus

ABSTRACT

A heat pump apparatus includes: a refrigerant circuit, which is configured to circulate refrigerant, and includes a compressor, a heat source heat exchanger, an expansion mechanism, and an intermediate heat exchanger which are sequentially connected through a pipe; and a fluid circuit, which is configured to circulate a fluid, and includes the intermediate heat exchanger, a load heat exchanger, and a check valve which are sequentially connected through a pipe. A pressure regulating valve is provided to the heat pump apparatus. The pressure regulating valve is connected to a pipe connecting an outlet of the intermediate heat exchanger and an inlet of the load heat exchanger, and is configured to interrupt a flow passage of the fluid when the refrigerant leaks to the fluid, and pressure of the fluid is increased.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national stage application of InternationalApplication No. PCT/JP2016/086735, filed on Dec. 9, 2016, the contentsof which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a heat pump apparatus, and moreparticularly, to leakage of refrigerant in the heat pump apparatus.

BACKGROUND

Hitherto, there has been known a heat pump apparatus to be used in anair-conditioning apparatus, a refrigeration apparatus, or other similarapparatus. A heat pump apparatus described in Patent Literature 1includes a refrigerant circuit configured to circulate refrigerant and afluid circuit configured to circulate a fluid. The refrigerant circuitincludes a compressor, a heat source heat exchanger, an expansionmechanism, and an intermediate heat exchanger, which are sequentiallyconnected through pipes to form a circuit. The fluid circuit includesthe intermediate heat exchanger, a first valve, a load heat exchanger,and a second valve, which are sequentially connected through pipes toform a circuit. Further, in order to cope with leakage of therefrigerant, the heat pump apparatus described in Patent Literature 1includes a leakage detection device configured to detect that therefrigerant circulating through the refrigerant circuit is leaked fromthe intermediate heat exchanger to the fluid, and a controllerconfigured to close the first valve and the second valve connected tothe fluid circuit when the leakage detection device detects the leakageof the refrigerant. In the heat pump apparatus, when the refrigerant isleaked from the refrigerant circuit to the fluid circuit, the firstvalve and the second valve are closed by the controller, therebypreventing the refrigerant thus leaked from flowing beyond the firstvalve and the second valve.

PATENT LITERATURE

Patent Literature 1: International Patent WO 2013/038577 A1

In the heat pump apparatus in Patent Literature 1, both of the leakagedetection device and the controller configured to close the first valveand the second valve use electric power as a power source, and cannot beoperated under a state in which the electric power is not supplied.However, even under a state in which the electric power is not suppliedso that the leakage detection device and the controller are shut down,there is a risk of causing breakage of the intermediate heat exchangerdue to corrosion and breakage of the intermediate heat exchanger due tofreezing caused by temperature decrease. In such a case, the leakage ofthe refrigerant cannot be detected, and further, there is a risk in thatthe refrigerant thus leaked cannot be prevented from flowing beyond thefirst valve and the second valve. As a result, there is a risk in thatthe refrigerant may be leaked to an indoor space in which the load heatexchanger of the fluid circuit is arranged.

SUMMARY

The present invention has been made to overcome the problem describedabove, and an object of the present invention is to provide a heat pumpapparatus capable of preventing leakage of refrigerant to an indoorspace even when the refrigerant is leaked under a state in whichelectric power is not supplied.

According to one embodiment of the present invention, there is provideda heat pump apparatus, including: a refrigerant circuit in whichrefrigerant circulates, the refrigerant circuit being formed byconnecting in order, by pipes, a compressor, a heat source heatexchanger, an expansion mechanism, and an intermediate heat exchanger; afluid circuit in which a fluid circulates, the fluid circuit beingformed by connecting in order, by pipes, the intermediate heatexchanger, a load heat exchanger, and a check valve; and a pressureregulating valve arranged in the fluid circuit and connected to a pipeconnecting an outlet of the intermediate heat exchanger and an inlet ofthe load heat exchanger, the pressure regulating valve being configuredto interrupt a flow passage of the fluid when the refrigerant leaks tothe fluid and pressure of the fluid is increased.

In the heat pump apparatus according to one embodiment of the presentinvention, the pressure regulating valve is configured to interrupt theflow passage of the fluid when the refrigerant leaks to the fluidcirculating through the fluid circuit, and the pressure of the fluid isincreased. The pressure regulating valve is connected to the pipeconnecting the outlet of the intermediate heat exchanger and the inletof the load heat exchanger. Therefore, even under a state in which theelectric power is not supplied to the heat pump apparatus, in theintermediate heat exchanger, the refrigerant leaking to the fluid can beprevented from reaching the load heat exchanger. As a result, theleakage of the refrigerant to the indoor space can be prevented.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of configuration of an air-conditioningapparatus of Embodiment 1 of the present invention.

FIG. 2 is a schematic diagram of configuration of a pressure regulatingvalve of Embodiment 1.

FIG. 3 is a diagram for illustrating flows of refrigerant and water inthe air-conditioning apparatus of Embodiment 1 during a heatingoperation.

FIG. 4 is a diagram for illustrating an operation of the pressureregulating valve of Embodiment 1 during the heating operation.

FIG. 5 is a diagram for illustrating the flows of the refrigerant andthe water in the air-conditioning apparatus of Embodiment 1 during acooling operation.

FIG. 6 is a diagram for illustrating the flows of the refrigerant andthe water when the refrigerant is leaked in the air-conditioningapparatus of Embodiment 1 during the heating operation.

FIG. 7 is a diagram for illustrating an operation of the pressureregulating valve of Embodiment 1 when the refrigerant is leaked duringthe heating operation.

FIG. 8 is a schematic diagram of configuration of an air-conditioningapparatus of Embodiment 2 of the present invention.

FIG. 9 is a diagram for illustrating the flows of the refrigerant andthe water when the refrigerant is leaked in the air-conditioningapparatus of Embodiment 2 during the heating operation.

DETAILED DESCRIPTION

Now, heat pump apparatus according to embodiments of the presentinvention are described in detail by referring to the drawings. Notethat, the present invention is not limited to the embodiments describedbelow. Moreover, in the drawings referred to below, sizes of componentsmay be different from the reality in some cases.

Embodiment 1

FIG. 1 is a schematic diagram of configuration of an air-conditioningapparatus of Embodiment 1 of the present invention. An air-conditioningapparatus 1 includes a refrigerant circuit 20 including a compressor 2,a four-way valve 3, a heat source heat exchanger 6, an expansion valve5, and an intermediate heat exchanger 4, which are sequentiallyconnected through pipes to form a circuit. Further, the air-conditioningapparatus 1 includes a water circuit 30 including the intermediate heatexchanger 4, a pressure regulating valve 7, a load heat exchanger 8, apump 9, and a check valve 10, which are sequentially connected throughpipes to form a circuit. A flammable refrigerant such as the R32refrigerant or propane is circulating through the refrigerant circuit20, and water is circulating through the water circuit 30. In the watercircuit 30, an air purge valve 11 is connected to a pipe branching froma pipe connecting the pressure regulating valve 7 and the load heatexchanger 8, and a load safety valve 12 is connected to a pipe branchingfrom a pipe connecting the load heat exchanger 8 and the pump 9.

The load heat exchanger 8 is installed in an indoor space being a targetto be air-conditioned. In the water circuit 30, the pressure regulatingvalve 7 is connected to a pipe connecting an outlet of the intermediateheat exchanger 4 and an inlet of the load heat exchanger 8. The checkvalve 10 is a valve configured to allow water to flow from the pump 9 tothe intermediate heat exchanger 4 in the water circuit 30, and toinhibit water from flowing from the intermediate heat exchanger 4 to thepump 9 in the water circuit 30.

The check valve 10 is connected in the water circuit 30 to a pipeconnecting an outlet of the load heat exchanger 8 and an inlet of theintermediate heat exchanger 4. The air purge valve 11 is a valveconfigured to exhaust air generated in or mixed into the water circuit30 to the outside, and to prevent idle running of the pump 9. In orderto exhaust the air efficiently, the air purge valve 11 is connected to apipe branching from a pipe located at an upper most position in thewater circuit 30. The load safety valve 12 is a valve configured todrain the water to suppress pressure increase when pressure in the watercircuit 30 is increased. Therefore, the load safety valve 12 isconnected to a pipe, which is branched from the vicinity of an inflowside of the pump 9, so as not to be operated by an influence of pressureincrease in the pump 9. That is, the air purge valve 11 and the loadsafety valve 12 are installed in the indoor space. In order to exchangeheat between the air and the refrigerant, the heat source heat exchanger6 is accommodated in an outdoor unit installed in an outdoor space.

(Configuration of Pressure Regulating Valve 7)

FIG. 2 is a schematic diagram of configuration of the pressureregulating valve of Embodiment 1. Referring to FIG. 2, a configurationof the pressure regulating valve 7 of Embodiment 1 is described. Thepressure regulating valve 7 is a valve which is usable only in onedirection, and has one inlet and one outlet. The pressure regulatingvalve 7 has a machine space 7A being a space that water does not flowinto, and a water flow part 7B through which water flows. Further, thepressure regulating valve 7 includes a diaphragm 71, a shaft 72, a coilspring 73, a closing plate 74, and an inner wall 75.

The inner wall 75 is configured to partition an inlet-side water flowpart 7BA corresponding to an inflow side of the water flow part 7B, andan outlet-side water flow part 7BB corresponding to an outflow side ofthe water flow part 7B. An opening portion 75A is formed in the innerwall 75. The diaphragm 71 is arranged in the inlet-side water flow part7BA, and is configured to partition the machine space 7A and the waterflow part 7B. The diaphragm 71 is a member which is deformable in anup-and-down direction in FIG. 2 in accordance with pressure. The shaft72 is a longitudinal member inserted through the opening portion 75A ofthe inner wall 75 while being supported by the diaphragm 71. The shaft72 is arranged so that one distal end thereof is located in theoutlet-side water flow part 7BB and an other distal end thereof islocated in the machine space 7A. The closing plate 74 is arranged on anend portion of the shaft 72, which is located in the outlet-side waterflow part 7BB. An end portion of the shaft 72, which is located in themachine space 7A, is received in a receiving portion 7C formed in themachine space 7A. The closing plate 74 has an area larger than anopening area of the opening portion 75A.

In the machine space 7A, the coil spring 73 being a spring member iswound around the shaft 72. One end portion of the coil spring 73 isfixed to an inner peripheral surface of the pressure regulating valve 7,which forms the machine space 7A, and an other end portion thereof isfixed to the diaphragm 71. The coil spring 73 urges the diaphragm 71 ina downward direction. The shaft 72 is moved in an upward directionagainst the force of the coil spring 73. With this, the opening portion75A of the inner wall 75 is closed by the closing plate 74, and a flowpassage connecting the inlet-side water flow part 7BA and theoutlet-side water flow part 7BB is interrupted. In Embodiment 1, theshaft 72 and the closing plate 74 correspond to a closing mechanism.

When the water is circulating through the water circuit 30, the waterflows from an inlet of the pressure regulating valve 7 toward an outletthereof. At this time, a force in the upward direction is applied to thediaphragm 71 due to water pressure. That is, when the water iscirculating through the water circuit 30, the force of the coil spring73 in the downward direction is applied to the diaphragm 71, and theforce in the upward direction due to the water pressure is also appliedto the diaphragm 71. Therefore, the diaphragm 71 is deformed in anapplying direction of a force, which is greater of the force due to thewater pressure and the force of the coil spring 73. In Embodiment 1, asthe coil spring 73, there is selected a spring having a springcoefficient large enough to push down the shaft 72 in the downwarddirection against the water pressure to prevent the closing plate 74from closing the opening portion 75A of the inner wall 75 andinterrupting the flow passage of the water during a heating operation, acooling operation, and a defrosting operation at a normal time duringwhich the refrigerant is not leaked to the water circuit 30. Therefore,as illustrated in FIG. 2, by the force of the coil spring 73, thediaphragm 71 is deformed against the water pressure in the downwarddirection, that is, in a direction toward the opening portion 75A of theinner wall 75. In association with the deformation of the diaphragm 71,the shaft 72 is moved in the downward direction, and the closing plate74 is located at a position away from the opening portion 75A.

(Heating Operation)

Referring to FIG. 3, an operation during the heating operation, whichrelates to Embodiment 1, is described. FIG. 3 is a diagram forillustrating flows of refrigerant and water in the air-conditioningapparatus of Embodiment 1 during the heating operation. In FIG. 3, solidarrows indicate the flow of the refrigerant, and broken arrows indicatethe flow of the water. During the heating operation of theair-conditioning apparatus 1, in the refrigerant circuit 20, refrigerantcompressed into a high-temperature, high-pressure state by thecompressor 2 passes through the four-way valve 3 and flows into theintermediate heat exchanger 4. The refrigerant flowing into theintermediate heat exchanger 4 is subjected to heat exchange with watercirculating through the water circuit 30, and is condensed into liquidrefrigerant. At this time, the water circulating through the watercircuit 30 is heated. The liquid refrigerant passes through theexpansion valve 5 and is expanded into low-temperature and low-pressuretwo-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerantflows into the heat source heat exchanger 6, and is subjected to heatexchange with outdoor air to be evaporated into gas refrigerant. The gasrefrigerant passes through the four-way valve 3, and is sucked into thecompressor 2 again to be compressed into a high-temperature,high-pressure state.

Meanwhile, in the water circuit 30, the high-temperature water heated inthe intermediate heat exchanger 4 passes through the pressure regulatingvalve 7, and flows into the load heat exchanger 8. The high-temperaturewater flowing into the load heat exchanger 8 is subjected to heatexchange with indoor air to be cooled. At this time, the indoor air isheated. The cooled water sequentially passes through the pump 9 and thecheck valve 10 and flows into the intermediate heat exchanger 4 again.

An operation of the pressure regulating valve 7 during the heatingoperation is described. FIG. 4 is a diagram for illustrating theoperation of the pressure regulating valve of Embodiment 1 during theheating operation. As described above, the coil spring 73 of thepressure regulating valve 7 has a spring coefficient large enough topush down the shaft 72 in the downward direction against the waterpressure to prevent the closing plate 74 from interrupting the flowpassage of the water due to the pressure of the water passing throughthe pressure regulating valve 7. Therefore, during the heatingoperation, the coil spring 73 of the pressure regulating valve 7 pushesdown the diaphragm 71, and pushes down the shaft 72 and the closingplate 74. As a result, in the pressure regulating valve 7, the flowpassage is formed between the inlet-side water flow part 7BA and theoutlet-side water flow part 7BB, and the high-temperature water flowinginto the pressure regulating valve 7 through the inlet flows outtherefrom through the outlet.

(Cooling Operation)

Referring to FIG. 5, an operation during the cooling operation, whichrelates to Embodiment 1, is described. FIG. 5 is a diagram forillustrating the flows of the refrigerant and the water in theair-conditioning apparatus of Embodiment 1 during the cooling operation.In FIG. 5, solid arrows indicate the flow of the refrigerant, and brokenarrows indicate the flow of the water. During the cooling operation, inthe refrigerant circuit 20, refrigerant compressed into ahigh-temperature, high-pressure state by the compressor 2 passes throughthe four-way valve 3 and flows into the heat source heat exchanger 6.The refrigerant flowing into the heat source heat exchanger 6 issubjected to heat exchange with air to be turned into liquidrefrigerant. The liquid refrigerant passes through the expansion valve 5and is expanded into low-temperature and low-pressure two-phasegas-liquid refrigerant. The two-phase gas-liquid refrigerant flows intothe intermediate heat exchanger 4, and is subjected to heat exchangewith water to be evaporated into gas refrigerant. At this time, thewater circulating through the water circuit 30 is cooled. The gasrefrigerant passes through the four-way valve 3, and is sucked into thecompressor 2 again to be compressed into a high-temperature,high-pressure state.

Meanwhile, in the water circuit 30, the low-temperature water cooled inthe intermediate heat exchanger 4 passes through the pressure regulatingvalve 7, and flows into the load heat exchanger 8. The low-temperaturewater flowing into the load heat exchanger 8 is subjected to heatexchange with the indoor air to be heated. At this time, the indoor airis cooled. The heated water sequentially passes through the pump 9 andthe check valve 10 and flows into the intermediate heat exchanger 4again.

An operation of the pressure regulating valve 7 during the coolingoperation is described. Similarly to the case during the heatingoperation, as illustrated in FIG. 4, in the pressure regulating valve 7,the flow passage is formed between the machine space 7A and the waterflow part 7B, and the low-temperature water flowing into the pressureregulating valve 7 through the inlet flows out therefrom through theoutlet.

(Defrosting Operation)

An operation of the air-conditioning apparatus 1 of Embodiment 1 duringthe defrosting operation is described. The defrosting operation isexecuted when frost is formed on the heat source heat exchanger 6 by theheating operation. The operation during the defrosting operation issimilar to the operation during the cooling operation. That is, asillustrated in FIG. 5, in the refrigerant circuit 20, the refrigerantcompressed into a high-temperature, high-pressure state by thecompressor 2 passes through the four-way valve 3, and flows into theheat source heat exchanger 6. The frost formed on the heat source heatexchanger 6 is melted and removed by the high-temperature andhigh-pressure refrigerant flowing into the heat source heat exchanger 6.The other operation is similar to the operation during the coolingoperation.

(When Refrigerant is Leaked)

As described above, during the cooling operation and the defrostingoperation, the low-temperature refrigerant flows into the intermediateheat exchanger 4, and cools the water flowing through the intermediateheat exchanger 4. Therefore, depending on circumstances, the waterflowing through the intermediate heat exchanger 4 may be frozen, andthere is a risk in that the intermediate heat exchanger 4 may be brokendue to cubical expansion of the water caused by the freezing. Further,there is a risk in that fatigue fracture caused by the pressure increasemay occur in the intermediate heat exchanger 4 due to the breakagecaused by abnormal increase of pressure of the refrigerant or as aresult of repetitive operations. Further, thinning of the intermediateheat exchanger 4 caused by corrosion of components of the intermediateheat exchanger 4 may lead to decrease in strength of the intermediateheat exchanger 4, and there is also a risk in that the breakage of theintermediate heat exchanger 4 may be promoted.

When the intermediate heat exchanger 4 is broken, due to a difference inpressure between the refrigerant flowing through the refrigerant circuit20 and the water flowing through the water circuit 30, the refrigerantis mixed into the water circuit 30. When the refrigerant is mixed intothe water circuit 30, the refrigerant is gasified due to an effect ofpressure reduction, thereby causing increase of the pressure in thewater circuit 30. When the pressure in the water circuit 30 isincreased, the water is drained through the load safety valve 12 mountedin the water circuit 30. At this time, through the drainage of water,the refrigerant mixed into the water inside the water circuit 30 isexhausted to the indoor space. As a result, a flammable region isformed, and when the flammable region reaches an ignition source, thereis a risk of causing ignition. Similarly, the gasified refrigerant mixedinto the water circuit 30 is exhausted through the air purge valve 11and forms the flammable region, with the result that there is a risk ofcausing ignition. However, in Embodiment 1, the pressure regulatingvalve 7 is provided. Thus, the refrigerant is prevented from beingexhausted to the indoor space and forming the flammable region.

Now, an operation of the pressure regulating valve 7 of Embodiment 1when the refrigerant is leaked is described. FIG. 6 is a diagram forillustrating the flows of the refrigerant and the water when therefrigerant is leaked in the air-conditioning apparatus of Embodiment 1during the heating operation. FIG. 7 is a diagram for illustrating anoperation of the pressure regulating valve of Embodiment 1 when therefrigerant is leaked during the heating operation. When the refrigerantis leaked, the refrigerant leaks to the water circulating through thewater circuit 30. With this, the water pressure of the water flowinginto the pressure regulating valve 7 through the inlet thereof isincreased to be greater than the force of the coil spring 73 of thepressure regulating valve 7. As a result, the diaphragm 71 is deformedupward, that is, in a direction to be away from the opening portion 75Aof the inner wall 75 against the force of the coil spring 73. The shaft72 is moved in association with the deformation of the diaphragm 71.With this, as illustrated in FIG. 7, the closing plate 74 is located ata position at which the closing plate 74 closes the opening portion 75A.When the opening portion 75A of the inner wall 75 is closed by theclosing plate 74, in the pressure regulating valve 7, the flow passagefrom the inlet-side water flow part 7BA to the outlet-side water flowpart 7BB is interrupted, thereby preventing the water, which flows intothe pressure regulating valve 7 through the inlet thereof, from flowingout of the pressure regulating valve 7 through the outlet thereof.Further, the flow passage is interrupted so that the water pressureapplied to the inlet of the pressure regulating valve 7 is furtherincreased, thereby also increasing the pressure of pressing the closingplate 74 against a peripheral edge of the opening portion 75A of theinner wall 75 by the diaphragm 71 and the shaft 72. As a result, anamount of the refrigerant leaking to the water circulating through thewater circuit 30 is reduced.

As described above, in Embodiment 1, the pressure regulating valve 7 isconfigured to be operated when the water pressure is increased due tothe leakage of the refrigerant to the water circulating through thewater circuit 30. Therefore, even under a state in which electric poweris not supplied to the air-conditioning apparatus 1, when a situation ofleakage of the refrigerant occurs, the flow passage in the water circuit30 is interrupted by the pressure regulating valve 7, thereby preventingthe leakage of the refrigerant to the indoor space.

Further, in the air-conditioning apparatus described in PatentLiterature 1, a time period is required from detection by a leakagedetection device to interruption by a first valve and a second valve.Therefore, there is a risk in that the refrigerant thus leaked may flowfurther beyond the first valve and the second valve. As a result, thereis a risk in that the refrigerant may be leaked to the indoor space inwhich a load heat exchanger of a fluid circuit is arranged. On the otherhand, according to Embodiment 1, the pressure regulating valve 7 isoperated in response to the increase in water pressure caused by theleakage of the refrigerant. Thus, the flow passage can be interrupted ina short period of time. Therefore, the amount of the refrigerant leakingto the water circuit 30 can be reduced.

The pressure regulating valve 7 is interposed at the pipe connecting theoutlet of the intermediate heat exchanger 4 and the inlet of the loadheat exchanger 8 at a portion between the outlet of the intermediateheat exchanger 4 and the air purge valve 11. Therefore, the refrigerantleaking to the water inside the water circuit 30 is prevented fromreaching the air purge valve 11. As a result, the leakage of therefrigerant to the indoor space is prevented.

Further, through interruption of the flow passage of the water in thepressure regulating valve 7, the flow of the water in the water circuit30 is stopped, and the check valve 10 is set to a closed state. As aresult, the refrigerant leaked from the intermediate heat exchanger 4and flowing into the water circuit 30 is prevented from flowing from thepressure regulating valve 7 and the check valve 10 to a side on whichthe load heat exchanger 8 is located, thereby preventing the refrigerantfrom reaching the air purge valve 11 and preventing the refrigerant fromreaching the load safety valve 12. Therefore, the leakage of therefrigerant to the indoor space can be prevented. Further, the pressureincrease of the water flowing through the load heat exchanger 8, pipesextending throughout the indoor space, and welding portions of the pipescan be prevented. Therefore, the water including the refrigerant can beprevented from leaking exceeding the pressure resistance of the loadheat exchanger 8, the pipes in the indoor space, and the weldingportions of the pipes.

Embodiment 2

FIG. 8 is a schematic diagram of configuration of an air-conditioningapparatus of Embodiment 2 of the present invention. Embodiment 2 isdifferent from Embodiment 1 in that an outdoor-space safety valve 13 isconnected to a pipe branching from a pipe connecting the intermediateheat exchanger 4 and the pressure regulating valve 7. Operatingpressure, that is, valve opening pressure of the outdoor-space safetyvalve 13 is equal to or higher than operating pressure of the closingplate 74 of the pressure regulating valve 7, that is, fluid interruptionpressure of the pressure regulating valve 7. In other words, the fluidinterruption pressure of the pressure regulating valve 7 is equal to orlower than the operating pressure of the outdoor-space safety valve 13.It is desired that the valve opening pressure of the outdoor-spacesafety valve 13 be higher than the operating pressure of the closingplate 74. Further, it is desired that the outdoor-space safety valve 13and a drain outlet extending from the outdoor-space safety valve 13 beinstalled in an open space such as an open-air space or a room having alarge floor area.

In Embodiment 2, a heating operation, a cooling operation, and adefrosting operation are executed in a manner similar to those inEmbodiment 1 described above, and hence description thereof is omitted.An operation of the air-conditioning apparatus 1 of Embodiment 2 whenthe refrigerant is leaked from the intermediate heat exchanger 4 to thewater circuit 30 is described. FIG. 9 is a diagram for illustrating theflows of the refrigerant and the water when the refrigerant is leaked inthe air-conditioning apparatus of Embodiment 2 during the heatingoperation. In FIG. 9, solid arrows indicate the flow of the refrigerant,and broken arrows indicate the flow of the water. When the refrigerantis leaked from the intermediate heat exchanger 4 to the water circuit30, and the pressure of the water circulating through the water circuit30 is increased, the pressure regulating valve 7 is operated tointerrupt the flow passage of the water. Such an operation is similar tothe operation in Embodiment 1 described above. In Embodiment 2, afterthe leakage of the refrigerant, when the pressure increase of the waterinside the water circuit 30 is continued so that the pressure of thewater inside the water circuit 30 exceeds the operating pressure of theoutdoor-space safety valve 13, the outdoor-space safety valve 13releases the water and the refrigerant to the open space. Then, thepressure in the water circuit 30 is gradually reduced. Through thereduction of the pressure in the water circuit 30, the outdoor-spacesafety valve 13 is closed, and the release of the water and therefrigerant to the open space is stopped.

According to Embodiment 2, the outdoor-space safety valve 13 is providedon the pipe branching from the pipe connecting the intermediate heatexchanger 4 and the pressure regulating valve 7. Therefore, it ispossible to prevent the refrigerant flowing into the water circuit 30through the broken part of the intermediate heat exchanger 4 fromreaching the indoor space, and to prevent the increase of the pressureapplied to the pipe connecting the check valve 10 and the intermediateheat exchanger 4 and the pipe connecting the intermediate heat exchanger4 and the pressure regulating valve 7. Further, when the refrigerant isleaked, the increase of the pressure applied to those pipes isprevented. Thus, components having low resistance to back pressure canbe used for the pressure regulating valve 7, the check valve 10, and thepipe connecting each of the pressure regulating valve 7 and the checkvalve 10 to the intermediate heat exchanger 4. That is, componentshaving special specification do not need to be prepared for the pressureregulating valve 7, the check valve 10, and the pipe connecting each ofthe pressure regulating valve 7 and the check valve 10 to the heatexchanger 4. Thus, this configuration is economical.

1. A heat pump apparatus comprising: a refrigerant circuit in whichrefrigerant circulates, the refrigerant circuit being formed byconnecting in order, by pipes, a compressor, a heat source heatexchanger, an expansion mechanism, and an intermediate heat exchanger; afluid circuit in which a fluid circulates, the fluid circuit beingformed by connecting in order, by pipes, the intermediate heatexchanger, a load heat exchanger, and a check valve; and a pressureregulating valve arranged in the fluid circuit and connected to a pipeconnecting an outlet of the intermediate heat exchanger and an inlet ofthe load heat exchanger, the pressure regulating valve being configuredto interrupt a flow passage of the fluid when the refrigerant leaks tothe fluid and pressure of the fluid is increased.
 2. The heat pumpapparatus of claim 1, wherein the pressure regulating valve includes aflow part through which the fluid flows, and a space that the fluid isprevented from flowing into, an inner wall configured to partition aninflow side of the flow part and an outflow side of the flow part, adiaphragm arranged on the inflow side and configured to partition thespace and the flow passage, and to be deformed in accordance with thepressure, a closing mechanism configured to be moved in association withthe deformation of the diaphragm to open and close an opening portionformed in the inner wall; and a spring configured to deform thediaphragm by applying a force to the diaphragm to move the closingmechanism to a position at which the closing mechanism is prevented fromclosing the opening portion, and wherein the spring is configured tohave a force set such that, under a state in which the refrigerant isnot leaking, the diaphragm is deformed against the pressure of the fluidby the force, to prevent the opening portion from being closed by theclosing mechanism, and that, under a state in which the refrigerant isleaking, the diaphragm is deformed against the force, by the pressure ofthe fluid increased due to leakage of the refrigerant so that theopening portion is closed by the closing mechanism.
 3. The heat pumpapparatus of claim 2, wherein the closing mechanism includes a shaftbeing a longitudinal member, inserted through the opening portion whilebeing supported by the diaphragm, and arranged so that one distal end ofthe shaft is located on the outflow side and an other distal end of theshaft is located in the space; and a closing plate arranged on the onedistal end of the shaft, wherein the spring is wound around the shaft inthe space, wherein, under the state in which the refrigerant is notleaking, the diaphragm is deformed in a direction toward the openingportion by the force of the spring against the pressure of the fluid,and the shaft is moved in association with the deformation of thediaphragm so that the closing plate is located at a position away fromthe opening portion, and wherein, under the state in which therefrigerant is leaking, the diaphragm is deformed in a direction to beaway from the opening portion by the pressure of the fluid increased dueto the leakage of the refrigerant against the force of the spring, andthe shaft is moved in association with the deformation of the diaphragmso that the closing plate is located at a position at which the closingplate closes the opening portion.
 4. The heat pump apparatus of claim 1,further comprising an air purge valve configured to exhaust air insidethe fluid circuit to an outside of the fluid circuit, and connected to apipe branching from the pipe connecting the outlet of the intermediateheat exchanger and the inlet of the load heat exchanger, wherein thepressure regulating valve is interposed between the outlet of theintermediate heat exchanger and the air purge valve.
 5. The heat pumpapparatus of claim 1, further comprising a safety valve configured to beopened when the pressure in the fluid circuit is increased, and toexhaust the fluid to the outside of the fluid circuit to prevent theincrease of the pressure in the fluid circuit, wherein the safety valveis connected to a pipe branching from a portion between the check valveand the pressure regulating valve in a circulating direction of thefluid which flows from the check valve into an inlet of the intermediateheat exchanger and reaches the pressure regulating valve through theoutlet of the intermediate heat exchanger, and wherein the safety valveis configured to, when the refrigerant leaks to the fluid and thepressure in the fluid circuit is increased, exhaust the fluid includingthe refrigerant through the safety valve.
 6. The heat pump apparatus ofclaim 5, wherein fluid interruption pressure of the pressure regulatingvalve is set equal to or lower than operating pressure of the safetyvalve.
 7. The heat pump apparatus of claim 1, wherein the refrigerantcirculating through the refrigerant circuit is flammable, and the fluidcirculating through the fluid circuit is non-flammable.